1. Field of the Invention
The present invention relates to a device for supplying an image-forming medium such as paper or film and, more particularly, to a supply device for counting the number of supplied image-forming mediums to sense the life of feed rollers.
2. Description of the Related Art
A paper supply device is used in an image forming apparatus, such as a copying machine or a printer, so as to feed paper or film serving as an image forming medium to an image-forming section. Prior to the formation of an image, sheets of paper, for example, are stored in a paper feeding section. In forming the image the sheets of paper are taken out from the paper feeder one by one by means of frictional force between the paper and feed rollers and then fed to the image-forming section via some feed rollers. The friction with the feed rollers is indispensable to paper feed. Thus several tens of thousands of paper feeds will degrade surface characteristics of the feed rollers, lowering the feeding capability. It is thus necessary to sense the degradation of the feed rollers so as to replace feed rollers regularly. In a conventional copying machine, to sense the degradation or life of the feed rollers, the frequency of use of a developing unit used for copying is counted. With this method, however, it is difficult to determine the frequency of use of the feed rollers for feeding paper. Hence the time of replacement of the feed rollers is left to servicemen to decide. For this reason a device is desired which can accurately determine the frequency of use of the feed rollers to sense their degradation automatically.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a paper supply device which can accurately determine the frequency of use of feed rollers to sense their degradation or life automatically.
According to the present invention there is provided a paper supply device comprising a plurality of feeding means for feeding sheets of paper respectively, means for actuating one of the feeding means which is used for feeding the paper, means for respectively detecting the frequency of the use of the feeding means actuated by the actuating means, and means for indicating the result of the detection for the respective feeding means according to the frequency of the use of the feeding means detected by the detecting means.